Electromagnetic pump



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ELECTROMAGNETIC PUIIP Filed July 31 1951 3 Sheets-Sheet 1 InventorOLIVER OWEN PULLEY Attorney 1954 o. o, PULLEY 2,686,474

-- ELECTROMAGNETIC PUMP Filed July 31, 1951 3 Sheets-Sheet 2 InventorOLIVER OWEN PULLEY A Home y 8- 1954 o. o. PULLEY 2,685,474

ELECTROMAGNETIC PUMP Filed July 31. 1951 3 Sheets-Sheet 3 InventorOLIVER OWEN PULLEY Attorney Patented Aug. 17, 1954 umrao STATES PATENT"omen aces-,4" amc'rnomsomrrro rm Oliver Owen Pulley, Ablngdon, EnglandApplication July 31, 1951, Serial No. 239,459 Claims priority,'application Great Britain August 1, 195.-

4 Claims. (Cl. 108-1) This invention relates to electromagnetic pumpsfor electricity-conducting fluids such as liquid metals wherein thefluid is caused to flow along a duct in a gap in an iron circuit due tothe interaction of mutually perpendicular components of flux or currentin the fluid. Such pumps are referred to generally as electromagneticinteraction pumps.

It is convenient to classify the types 01' electromagnetic interactionpumps into two main classes, namely, conduction pumps and inductionpumps. A conduction pump is characterised in having externally connectedelectrodes for ieeding a current through the fluid in the duct while aninduction pump is characterised in that there are no externallyconnected electrodes but the current in the fluid in the duct is inducedtherein by a hanging magnetic flux. A conduction pump usually has theproperty of operating on either D. C. or A. C. but usually D. C. whilean induction pump is essentially an A. C. device although a rotating D.C. magnet may of course be used as a substitute for a rotating polyphasefleld.

In a further sub-classification conduction pumps are divided into threesub-classes, namely, linear, spiral and annular. A linear conduction pumis characterised in that the fluid duct. which is usually rectangular insection, traverses the iron circuit in a linear manner. Examples oi suchpumps are provided by United States Patent 2,397,785 and United StatesPatent 2,386,389. A spiral conduction pump is characterised in that thefluid duct follows a spiral path, an example of such a pump beingprovided by British Patent 528,091. An annular conduction pum ischaracterised in that the fluid duct is annular in section and such apump is referred to in the prior art discourse of British Patent528,091.

This invention is concerned with the linear conduction sub-class oielectromagnetic inter-- outlet end and a reduction at the inlet end,anda consequent-further distortion oi the fleld dis tribution.

These eflects have two consequences. Because the maximum local fleld islimited by the saturation value; of the iron circuit and. because of thewhere v a the anemia" l is the pump length and x a is the resistivity ofthe fluid The invention overcomes or reduces these eiiects and so makespossible the generation of higher pressures and removes theabove-mentioned limitation on the theoretical conversion efllciency.

The invention resides in a D. C. or single phase A. 0. linear conductionelectromagnetic interaction pump wherein the return conductor for thecurrent traversing the fluid in the duct passes back through the gap inthe iron circuit of the pump.

For the purpose oi this invention the phrase gap in the iron circuitmeans that part of the flux circuit in which the flux traverses thefluid duct or ducts and includes the part occupied by an iron betweentwo associated ducts.

In one form of the invention the gap is made 0! a' size just. toaccommodate the duct and return conductor so that the conductor is inphysical contact with the duct and one extremity of the gap.

In another form of the invention the gap in the iron-circuit is madelarger than that required to accommodate the duct and returnconductor'and laminations, stacked along the direction oi fluid flow inthe duct, are disposed between. the duct and-return conductor.

This latter form of the invention has particular application where thereturn conductor comprises an associated duct connected for series fluidflowwith the first duct.

Embodiments oi the invention as above statedandother ieatures oitheinvention are now do scribed with reference to. the accompanyingdrawings in which:.

Fig. l is a diagram showing flux distortion ina simple pump..

assure 3 1"ig.2isadiagramshowingcurrentdistortion inapump imilartothatoiPig. 1.

Fig. 3 is a perspective diagrammatic view of one pump according to theinvention.

Fig. 4 shows a modification to the return conductor arrangement of Pig.3.

Fig. 5 shows a modification to the conductor and duct arrangement ofFig. 3.

Fig. 6 shows a further modification to the conductor and ductarrangement of Fig. 3.

Fig. 7 is a perspective diagrammatic view of a two stage rectilinearpump according to the invention.

Fig. 8 is a perspective diagrammatic-view of another form of two-stagepump according to the invention.

In Fig. 1 a rectangular section duct H is located in a gap between polepieces I2, ll of an electromagnet. The direction of fluid flow along thechannel is indicated by the arrows H, the transverse current by thearrows It. the flux due to that current by the dotted line II and theflux through the pole pieces by dotted lines H. The flux is concentratedat the inlet end of the duct ll due to the interaction of flux lines IIand H.

In Fig. 2 a rectangular section duct ii is located in a gap between polepieces 22. 13 of an electromagnet. The direction of fluid flow along thechannel is indicated by the arrows 24 and the distribution of thetransverse current is indicated by arrow 28. The current is concentratedat the outlet end of the duct 2 i. This may be accounted for by the factthat with a concentrated flux at the inlet end (similar to that shown inPig. 1) the back E. M. F. generated in the fluid in the duct cuttingthat flux is larged. The current at the inlet end, with rapid fluidflow. may even be negative.

In Pig. 3 the pump has a rectangular duct 30 formed. as a flattenedportion of the stainless steel tube Ila so as to have narrow side wallsII and wide side walls 32. The duct is is situated between the polefaces 38 of an electromagnet 34 having an energizing winding 36. so thata flux can be set up in the direction of the arrow o to traverse theduct 8|. Electrical connections to the duct comprise an electrode llbrazed to one wall ll and an electrode 31 brazed to the other wall ll ofthe duct 30. A connection is made to electrode II by connector ll and aconnection is made to electrode 31 by sheet conductors 31a, 31b Joinedto a common connector ll. In operation of the pump with liquid metal inthe duct II current passes through the liquid metal from electrode 30 toelectrode 31. This current interacts with the flux passing at rightangles to the current so that a pressure is set up in the liquid metalat right angles to both the current and the flux; that is. the liquidmetal is caused to flow along the duct II. The current that has passedacross the duct II is returned by way of sheet conductors Ila and 81b sothere is no net current in the gap and consequently no flux due to thatcurrent. The field in all points across the gap remains uniform andequal to the impressed fleld.

m rig. 4 the duct I between pole pieces II, II is fed with currenttransversely by connectors II. N. A return current path from connector54 is provided through slots II in pole piece ll by conductors such asconductor ll. These condoctors may be brazed on to a common connectorsuch as connector 81.

In Fig. 5 two associated ducts II. II areprovidedandconnectedvialoopflsoastoprovide through the gap between polepieces duct II and connector .1. Loop I2 is such that negligible leakagecurrent through it.

Fig. 6 theassociated ducts II. II are inpass between pole pieces 12, IIandthespacebetweenthemlsfllledwithlamithe ducts whilst not substantiallyaflecting the reluctanceofthemainfluxpathbetweenthepole pieces. As therecan be no appreciable flux transverse to the laminated portion of theiron circuit there is no appreciable transverse flux in the remainder ofthe magnetic circuit and hence no distorting fleld in the gaps. Byspacing the ducts 1|, 1| a better flow path for the fluid is obtained inso far as sharp bends are avoided. By increasing the spacing evenfurther than shown in Fig. 6 the curvature given to the flow path canbeminimiseduntiltheextremecaseisreached as showninFigJi. Inthisflgurethe gapintheiron circuit is very large and consequently the two stagesof pumping may be carried out rectilinearly. The iron circuit consistsof yoke II. the duct ll carries the electrical conducting fluid.electrical connector I2, II are provided for current connection andinterconnection l4 completes the cin'rent path between the two stages ofthe pump. A laminated section ss together with the duct ll fill the gapin the iron circuit. The length of duct between connectors 82 and 83must be made long enough to reduce current leakage in a direction alongthe duct II to a tolerable minimum.

In Fig. a. the current path is made rectilinear and the fluid flow pathis looped. The U-shaped duct as is located between a yoke II andlamination It. Current connections as, 14, 85 are provided.

I claim:

1. A D. C. or single phase A. C. linear conduction electromagneticinteraction pump comprising, an iron yoke presenting two pole faces,means for setting up a flux in the yoke to cross the gap between thepole faces. a duct in the gap arranged to be traversed by the flux inone direction and having electrodes for the passage of current in adirection across the duct and angularly with respect to the flux, and anelectrical conductor connected to one of said electrodes and shaped topass through the gap between the pole faces in a direction opposite tothat taken by the current across the duct.

2. A D. C. or single phase A. C. linear conduction electromagneticinteraction pump comprising, an iron yoke presenting two flat polefaces. means for setting up a flux in the yoke to cross the gap betweenthe pole faces, two adjacent parallel rectangular-section ducts in saidgap arranged so that their broad faces are in parallel planes togetherwith the flat pole faces, electrodesforthepassageofcurrentacrossfluidinducts, an electrical connector joining together the two electrodes onone side of the gap and separate connectors to the electrodes on theother side of the I.

3. A D. C. or single phase A. 0. linear conduction electromagneticinteraction pump comprising, an iron yoke presenting two flat polefaces. meansforsettingupafluxintheyoketocrossthegapbetweenthepolefaceatwospacedpar- 3 allel rectangular section ductsin said up wrated from-each other by laminations stacked along thedirection of fluid now in the duct and arranged so that the broad facesof the ducts are in parallel planes together with the flat pole faces,an electrical conductor joining electrodes in the narrow faces of theducts on the one side and separate connectors to electrodes in thenarrow faces of the ducts on the other side.

4. A D. C. or single phase A. C. linear conduction electromagneticinteraction pump comprising, an iron yoke presenting two flat polefaces. a flat rectangular section duct passing in turn over said polefaces and in the plane of the pole faces, electrodes associated withsaid duct for feeding current across the duct at one pole face and backacross the duct at the other pole faceand a laminated iron assemblycompleting a flux path for flux in said core, the lamination being 6stacked for minimum reluctance in a ath I'Olllld the yoke andfor maximumreluctance in a direction of fluid flow along the duct.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,298,684 Chubb Apr. 1. 1919 1,660,407 Bainbrldge Rb. 28, 19281,792,449 Spencer Feb. 10, 1931 2,386,369 Thompson Oct. 9, 19452,389,218 Tama et a1. Nov. 20. 1945 2,397,785 Friedlander Apr. 2, 19462,539,800 Tama Jan. 30, 1951 FOREIGN PATENTS Number Country Date 511,137Germany June 20. 1928

